“Venus syndrome” is not a metaphor, it is a scientific scenario. The term should be self explanatory, but just to be clear, Venus syndrome is a scenario in which climate and atmospheric feedback loops are triggered that can’t be switched off. Under this scenario, as greenhouse gasses build up, and cause planetary warming, yet more greenhouse gasses are released which causes still more warming. This trajectory does not end in a balmy tropical resort Earth, but rather a planet that is closer to hell. Like Venus, Earth would become a pressure cooking inferno with virtually no life.